The increasing demand for data on fertility trends, contraceptive use, and child health in developing countries has led to the consolidation of several kinds of data collection within the main survey instrument used by the Demographic and Health Surveys (DHS) project. Revisions of the DHS core questionnaire have added questions on the health, vaccination status, and anthropometry of children under five years of age. There is strong evidence that in some countries these additional questions have caused some interviewers to omit or raise the ages of some children, thereby reducing their workload. Such omission or displacement leads to a downward bias in estimates of recent fertility and an upward bias in estimates of the accomplishments of the national family planning program. These effects have been most apparent in Pakistan, Indonesia, and Nigeria. - This project seeks to develop procedures to detect and adjust for such distortions, and to develop recommendations for changes in the survey instrument and/or field procedures that will minimize their occurrence in future surveys. The project will also attempt to identify the background patterns of misreporting of birthdates that are merely exacerbated by additional complexities in the questionnaires.